Technical Field
The present disclosure relates to a nano particle used to coat an electrode of a dye-sensitized solar cell.
Description of Related Art
With the recent growing concerns on the global warming, development of technologies utilizing environment-friendly energy has been drawing much of public attentions. Solar cell, being one of the most intriguing energy sources as such, study on this field has been diversified including silicon-based solar cells, thin film solar cells using inorganic materials such as copper indium gallium selenide (Cu(InGa)Se2; CIGS), dye-sensitized solar cells, organic solar cells, and organic-inorganic hybrid solar cells. Of them, the dye-sensitized solar cell, which is inexpensive and being drawn close to commercial application, has been highlighted in the fields of building-integrated photovoltaics (BIPV) and portable electronics.
Unlike other solar cells, the dye-sensitized solar cell absorbs visible light and produces electricity through a photoelectric conversion mechanism. In general, patterning of the titanium dioxide working electrode used in the dye-sensitized solar cell is prepared by a screen printing process. Screen printing is a printing technique in which a screen is placed on a work table and a paste is applied on a substrate as it is being passed through a patterned mesh using a rubber blade called the squeegee. The screen printing process is, however, disadvantageous in that it requires a great amount of expensive paste and it is applicable only to a flat substrate. Especially, the control of pattern intervals is important since the efficiency of the solar cell increases in proportion to the light receiving area. The limitation in the control of linewidth between electrodes has been pointed out as the shortcoming of the screen printing technique.
Recently, there has been proposed to form electrode by inkjet printing. This method has advantages that it reduces material loss and has secured control of narrow linewidths and its process is simple. The inkjet-based patterning process looks promising as a direct printing technique applicable not only to flat-panel displays but also to solar cells and other applications.
The inkjet process is advantageous in that, since a wanted pattern can be directly formed on a substrate using an inkjet head having small nozzles, the number of processes and material consumption decrease as compared to the screen printing technique and a desired pattern can be created using a simple computer software. However, because a highly viscous paste cannot be used in the inkjet method, printing has to be performed several times to accomplish an electrode coating with a predetermined thickness.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.